Consider the downlink transmission of an AP with \(N\)  antennas to \(K\)  single-antenna users. This transmission is aided by an IRS with \(M\)  phase shifters. A smart controller in the AP is responsible for managing the IRS by sharing information and coordinating the transmission. The power of the signals that are reflected by the IRS multiple times is much smaller than that of the signal reflected once, and thus it can be ignored [1]}. We consider an indoor application undergoing rich scattering propagation environment; hence, we consider only non-line-of-sight (NLOS) channels in our model [2]}, [3]}, [4]}, [5]}, [6]}.
